South Korea has delayed the third attempted launch of its Korea Space Launch Vehicle (KSLV) due to a faulty seal in the vehicle's Russian-built first stage. The launch will be delayed at least three days by the leak, as technicians must move the vehicle off the launch pad to replace the seal and make further inspections.

The leaky seal, which connects the liquid oxygen (LOx) and helium tanks, was visually confirmed after indications of a helium leak during the fueling process.

The stage uses helium to pressurize the fuel tanks, forcing fuel and liquid oxygen into the engines. The first stage, built by Russian company Khrunichev, uses LOx and kerosene to power a single RD-191 engine.

KSLV's first stage is also the same first stage in Russia's in-progress launch vehicle, the Angara series. Angara will, when the family is finalized, replace several distinct launch vehicle families with a common core, several of which can be combined for heavier payloads.

South Korea's previous two launch attempts with KSLV failed.

Source: Flight International